NGC7000, Deneb and surrounding (oldmiow)

NGC7000, Deneb and surrounding

Taken under bortle 6 sky at Taoyuan, Taiwan province, China (Taipei) with f/4.5 line scan lens.
This line scan lens is popular in the mainland China DIY lens community, they call it "Wine Red 90mm f/2.8 (酒紅90mm f/2.8 )" cuz the coating at rear glass reflect wine red color. Some users claim the image is pretty sharp and it can cover even medium format sensor.

The lens, focuser, mounting, etc cost me around 24USD (~6USD lens only)
My expectation before testing is that acceptable image could only cover APS-C sensor (good enough) and the color aberration might not be good. The actual aperture according to my entrance pupil measurement is very close f/4.5 but not f/2.8 as community claim.
I also tear the lens down and paint black (cheap marker) around the lens to improve the anti reflection around the lens.

Although it's not perfect, the overall image quality still impress me. The color aberration control is better than I thought, only some medium brightness stars show some purple/blue fringe. I only crop the image a little and coma toward the coners is still acceptable (just as I thought) especially at such a price. The halos around bright stars might come from my Nikon D5100 modified UV/IR cut filter from the size of halos.

2021/07/21 update: The halos around bright stars may also come from the lens itself and need further testing. I also remeasure the entrance pupil and get around 21mm, this lead to around f/4.28 aperture.

Please note: The following tables are updated every 24 hours.

Distribution of astrophotographers

This table shows the number of distinct astrophotographers who have been assigned and IOTD/TP award compared to the total number of images awarded.
	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

Distribution of subject types

This table shows the distribution of awards per subject type, compared to the popularity of images of that subject type.
	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
Noctilucent clouds
Landscape

Distribution of data sources

This table shows the distribution of awards per data source, compared to the popularity of images acquired from that data source.
	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown

The “AstroBin Image of the Day and Top Picks”, or IOTD/TP, is a long-running system to promote beautiful, interesting, peculiar, or otherwise amazing astrophotographs, with a focus on technical excellence. Learn more.

Submitted The date and time when you submitted this image for IOTD/TP consideration.	...
Views by Submitters (available since September 19th, 2023) Every image is assigned to 50% of available Submitters. In the event that at least 80% of them don't view the image before its time in the IOTD/TP process expires, it's assigned to the other 50% of Submitters and the process begins anew.
Promotions by Submitters When 3 distinct Submitters promote the image, it moves on to the next stage of the process: evaluation for Top Pick status. This requirement, in addition to anonymization of images and distribution to only a subset of them, prevents biases and ensures that the best images are selected.
Promotions by Reviewers When 3 distinct Reviewers promote the image, it moves on to the next stage of the process: evaluation for IOTD status.
Early dismissal Staff members have a lot of images to inspect on a daily basis, and they can dismiss images if they believe they don't meet the requirements for IOTD/TP selection. If an image is dismissed 5 times, it's removed from the process. This streamlines the process and ensures that any bias present in promotions could be overruled by other staff members.

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